In the moving averages guide you learned to read the direction of a trend with the EMA 9. But direction is only half the story. The EMA cannot tell you when a move has run too far, too fast.
Picture NABIL closing green nine days in a row, climbing the whole way. Something feels risky about buying right then, even though the trend is clearly up. That feeling has a name and a number, and the number is RSI.
What is RSI?
RSI stands for Relative Strength Index. Think of a rubber band. When a stock grinds higher day after day, the price stretches further from its recent normal level. Buyers who wanted in have mostly bought, the band is taut, and the risk of a snap-back grows. The same happens in reverse after a brutal fall: sellers get exhausted and a bounce becomes more likely.
RSI measures how stretched that rubber band is, as a single number from 0 to 100.
You want a single 0-to-100 momentum meter where a high number means the stock has risen too much lately and a low number means it has fallen too much. Looking only at daily closing prices, what would you actually measure to produce that number?
Reveal the answer
Compare the up-moves against the down-moves. If recent gains are bigger than recent losses, buyers are winning and the meter should read high. If losses dominate, it should read low. That comparison is exactly what RSI is built on.
How does RSI work?
You do not need the formula to use RSI, but the idea is simple and worth knowing. Over a window of days (the standard is 14), RSI compares the average size of the up-days against the average size of the down-days.
If recent gains are much bigger than recent losses, RSI rises toward 100. If losses dominate, it falls toward 0. A balanced tug-of-war sits near 50.
The extremes make the scale intuitive. A stock with only up-days in its window would read 100. Only down-days would read 0. That is why RSI is called a momentum indicator: it scores who has been winning lately, buyers or sellers, and by how much.
What do overbought and oversold mean?
Traders watch three reference lines on the 0-to-100 scale:
| RSI reading | What it suggests |
|---|---|
| Above 70 | Overbought. Risen a lot, stretched up. |
| Below 30 | Oversold. Fallen a lot, stretched down. |
| Around 50 | Neutral. No strong stretch either way. |
Practice spotting overbought and oversold
Tap New scenario and watch the RSI line in the lower panel swing between the zones. The line turns red in the overbought zone and green in the oversold zone:
RSI 84 · Overbought. Risen a lot lately. Stretched up. Do not chase; a strong stock can stay overbought.
Tap New scenario and watch the RSI line. When it climbs into the red zone above 70 the stock is overbought; when it drops into the green zone below 30 it is oversold. Illustrative data, not live NEPSE prices.
Try all three periods. A shorter RSI (9) reacts faster but hits the zones more often, while a longer RSI (21) is smoother and slower.
The 70/30 trap that burns beginners
NABIL has nine green days and its RSI climbs to 75, above the 70 overbought line. A beginner thinks: overbought means it is too high, so it must be about to crash, sell it. What could go wrong with treating RSI above 70 as an automatic signal to sell?
Reveal the answer
A fundamentally strong stock in a powerful uptrend can keep its RSI above 70 for weeks. If you sell every time RSI crosses 70, you get shaken out of your best winners again and again. On NEPSE a stock can also stay stretched because large players keep buying. RSI tells you a move is stretched, never why, so it is a warning, not a trigger.
Here is the mistake almost every new trader makes. They see RSI cross above 70 and think "overbought means it must crash, so sell." That reasoning is dangerous, for the reason the box above spells out: a stretched move is not a doomed one. RSI tells you the move is stretched, but never why, and a fundamentally strong stock can stay stretched for a long time.
RSI is a warning light, not a trigger. Above 70 means do not chase. Below 30 means do not panic-sell. It is context, not a command.
How to actually use RSI
- Treat the zones as context. Above 70 is "be careful," below 30 is "watch for a bounce."
- The more reliable moment is when RSI crosses back out of a zone (back below 70, or back above 30). That is momentum actually fading or reviving, not just stretching further.
- Use the 50 midline as a trend filter. RSI mostly above 50 leans bullish, mostly below 50 leans bearish. This pairs naturally with the EMA 9 from the previous article.
- Never act on RSI alone. Confirm it with trend and volume, which the next articles cover.
Key takeaways
- RSI scores momentum from 0 to 100 by comparing the size of recent gains against recent losses, usually over 14 days.
- Above 70 is overbought, below 30 is oversold, and 50 is the neutral midline.
- Overbought does not mean "sell now." Strong stocks can stay overbought for a long time, so treat 70 and 30 as warnings, not triggers.
- RSI is strongest when combined with the EMA 9 trend and volume, never used on its own.
Common questions
What is RSI in simple terms? A 0-to-100 momentum meter. High means the stock has risen a lot lately, low means it has fallen a lot.
Does RSI above 70 mean sell? No. A strong stock can stay above 70 for weeks. The better signal is RSI crossing back below 70.
What RSI period should I use on NEPSE? Start with the standard 14. Use a shorter period for faster signals and a longer one for smoother, slower ones.
Next we combine moving averages into a single momentum tool called the MACD, which is built directly from the EMAs you already know.
Educational content only. This is not investment advice. Prices shown are illustrative, not live NEPSE data.